Hydraulically operated machine tool table



Jilly 2- cc. FLYGARE I 2,290,832

HYDRAULICALLY OPERATED MACHINE TOOL TABLE Filed March 25, 1940 4 Sheets-Sheet 1 as 156 l 2 v Q CARI. G.F'L; IG'FARE' July 21, 1942. .c. G. FLYGARE 2,290,832

' HYDRAULICALLY OPERATED MKCHINE :001. TABLE Filed March 25 1940 4 Sheets- Sheet 2 CARL G. FLYG'AR y 1942- c G. FLYGARE 2,290,832

HYDRAULICALLY OPERATED MACHINE TOOL TABLE Filed March 25, 1940 4 Sheets-Sheet 3 I4 I] Z [6 5 20 ill 552 HE. E 1 2 9 Nil gwmm

CARL G. FLYGAR'E 1 1942 c. e. FLYGARE HYDRAULICALLY OPERATED MACHINE TOOL TABLE Filed March 25, 1940 4 Sheets-Sheet 4 ZS W Q EARL G. FLYG'ARE Patented July 21, 1942 HYDRAULICALLY OPERATED MACHINE TOOL TABLE Carl G. Flygare, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application March 25, 1949, Serial No. 325,733

1 Claim.

The invention relates to hydraulically operated machine tool tables or carriages and with regard to its more specific features to a hydraulic actuating and controlling mechanism for the reciprocatory traversing table or carriage of a grinding machine. This application is a continuation in part of my application Serial No. 224,338 filed August 11, 1938 (now abandoned).

One object of the invention is to improve the hydraulic system of the patent to Wallace H. Wood, No. 2,071,677. Another object of the invention is to provide apparatus of the type indicated with enough controls to vary the dwell at either end of the stroke of such a table or carriage. Another object of the invention is to provide a dwell control apparatus susceptible of adjustment to vary the dwell within wide limits. Another object of the invention is to hold a grinding wheel relatively stationary adjacent a shoulder on the work piece for one or more revolutions of said work piece. Another object of the invention is to provide a simple apparatus of the type indicated. Another object of the invention is to provide a fluid pressure actuating mechanism including a dwell control of simple and practical construction. Another object of the invention is to provide a grinder which can grind shouldered work accurately. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, all as will be illustrativ-ely described herein and the scope of the application of which will be indicated in the following claim.

In the accompanying drawings illustrating one of many possible embodiments of the mechanical features of this invention,

Figure 1 is a view partly in section and partly in diagram, illustrating a hydraulic actuating mechanism constructed in accordance with the invention;

Figures 2 and 3 are enlarged horizontal sectional views of the reversing valve, showing-the valve member in different positions;

Figure 4 is a sectional view taken on the line 4-4 of Figure 7;

Figure 5 is an end view of the reversing valve;

Figure 6 is a front elevation of the reversing controlling mechanism;

Figure 7 is a vertical sectional view on an enlarged scale of the reversing valve, showing part of the reversing lever and associated parts in front elevation; and

Figure 8 is a sectional view taken on the line 8-8 of Figure 7.

The invention, in its preferred form, makes use of the hydraulic operating mechanism of U. S. Letters Patent No. 2,071,677 issued on application of Wallace H. Wood, February 23, 1937.

Referring now to Figure 1, the machine embodying this invention comprises a base II] which supports a work table or carriage I I on the usual ways (not shown) for a longitudinal reciprocating movement relative to the base. It is well understood in the grinding machine art that reciprocatory movement of the table or carriage H is used to traverse a work piece (usually held by the table or carriage H) withrespect to a rotating grinding wheel for the grinding of the work piece. However, so far as the present invention is concerned, the grinding wheel may be mounted on the table or carriage and the present invention has application to external cylindrical grinders'for shaft grinding, also to surface grinders, internal grinders and other types. For grinding shafts having shoulders the invention is particularly useful because it is often desired to grind right up close to the shoulders, and such grinding requires accuracy of adjustment of the reciprocatory stroke of the table or carriage to within very close limits. Also when a grinding wheel or work piece is reciprocated, one with respect to the other, and no provision is made for causing the wheel to dwell at the ends of the stroke, there is a tendency to take off less metal at the ends of the stroke than in the intermediate portion thereof. In fact, if a constant speed reciprocatory traverse without any dwell be assumed, it will be seen that in any one complete reciprocation there will be parts of the work piece within the locus of the traverse which will not be touched by the grinding wheel. For this and other reasons a considerable dwell is desired in the motion of reciprocation of the table of a grinding machine and it is desirable to have the time of dwell adjustable.

Referring now to Figures 4 and 6, there are provided table dogs l2 and I3 adjustably mounted in a T-slot M on the front of the table or carriage II, the dogs being locked in the desired position of adjustment by cam or wedge devices operated by handles I5 and It. The dogs l2 and I3 have striking portions I! and 18 which alternately engage a pin or projection I9 on a reversing lever 20 which may also be operated by hand. The length of the stroke of the table or carriage as well as the position thereof relative to the other machine parts is determined by the setting of the dogs I 2 and I3, and the further mechanism to be described initiates reversal of the direction of traverse after the striking portion or |8 engages the projection l9. According to the present invention the striking portions l1 and I8 of the dogs I 2 and I3 may be in contact with the projection |9 of the reversing lever 20 for a long time at reversal, or the mechanism may be adjusted so that reversal is rapid at one end and slow at the other end. Furthermore, the present invention may involve an actual full stop of the table at reversal as distinguished from a slow creeping movement thereof. That is to say, the table may be maintained in stop position fora period of time measured even in minutes.

Referring now to Figure 1, a fluid pressure mechanism is provided to reciprocate the table I. In the form illustrated, a cylinder 39 is fastened to the under side of the table II. The cylinder contains a pair of spaced pistons 3| and 32 which are connected by a pair of hollow piston rods 33 and 34, respectively, with a pair of hollow brackets 35 and 36, respectively, which are fastened to opposite ends of the base l0.

In the preferred construction, the base H1 is box-like, the lower portion serving as a reservoir 31 for the fluid pressure system. Fluid is drawn from the reservoir through a pipe 4| by a pump 42 and is forced through a pipe 43 past a pipe 44 to a table control valve 45. A fluid pressure relief valve 49 is provided at the end of the pipe 44 to allow fluid under pressure to return to the reservoir through a pipe 41 in case the pressure within the system increases above a desired pressure.

The control valve 45 preferably combines the functions of a reversing valve and a pilot valve, so that the reversing lever 20 serves to move the valve member only to a median position and then fluid under pressure moves the valve member the remaining distance to effect reversal, producing thereby a smooth reversal of the table movement without the necessity of providing a plurality of valves. In the form illustrated, I provide a piston type valve member 49 having a plurality of pistons 59, 52, 53 and 54 integrally formed thereon. Fluid under pressure from the pump 42 is forced through the pipe 43 into a chamber 58 within the casing of the valve 45. The chamber 58 is directly connected to ports 59 and 60.

Referring now to Figures 1, 2, 3 and 7, between the pistons 5| and 52 is a movable valve chamber 6|. Between the pinions 52 and 53 is a corresponding but opposite valve chamber 62. There are provided ports 64 and 65 equally spaced from the center of the casing of the valve 45 which lead to chambers 66 and 61, respectively, which chambers are respectively connected to pipes 68 and 69 that are connected respectively to the hollow brackets 35 and 36. In the position of the valve piston 49 shown in Figure 1, the port 59 is uncovered and fluid is flowing through the port 64 and chamber 66 to pipe 98 to the left-hand side of the cylinder 38 and fluid is exhausting from the cylinder 39 via the pipe 99, chamber 61, port 65, chamber 62 through an exhaust port 19 located right between the ports 64 and 65.

Referring to Figures 1, 2, 3 and 7, outside of the ports 59 and 60 I provide narrow ports 11 and 18 which are connected with the main pressure chamber 58 and serve, at times, to admit fluid under pressure to chambers 19 and 80 for pilot actuation of the valve member 49. The chamber 19 is bounded by the piston portions 59 and 5|, the latter being larger, so that fluid under pressure in the chamber 19 urges the valve member 49 to the right. Similarly, the chamber is bounded by the piston portions 53 and 54, the former being larger, so that fluid under pressure in the chamber 80 urges the valve member 49 to the left.

In the preferred form of the present invention the reversal takes place in the following manner: One of the table dogs |2 or 3 strikes the pin |9 of the reversing lever 29. This, of course, moves the reversing lever but it is connected to the valve member 49 by a lost motion connection and a spring to be hereinafter described and, furthermore, the pilot pressure opposes movement of the valve member 49, so that the first action is to compress the spring and take up the lost motion. When this has happened, the valve member 49 must move if it be assumed that the table actuating force is greater than the pilot force, which it is. Assuming movement of the table to the left, as is consistent with Figures 1 and 6, the dog |3 strikes the pin l9 and after the aforesaid spring is compressed the valve member 49 is moved from the position shown in Figure 1, which is the position for the full traverse to the left, to the position shown in Figure 2. This stops the table because, as shown in Figure 2, not only is the port 59 cut off at this point in the movement of the valve member 49 but the exhaust port 10 is blocked and this looks the liquid in the right-hand side of the cylinder 30 and so effectively stops the table.

The dwell which is more particularly the subject of the present invention occurs while the valve member 49 is moving from the position shown in Figure 2 to the position shown in Figure 3, when the table is being reversed at the left-hand end of its stroke. The valve member 49 is moved during this dwell by the loaded spring above referred to which is backed up by the table. The table is absolutely stationary and, indeed, it cannot move because the liquid in the cylinder 30 cannot escape therefrom in either direction. For not only does the blocking of the exhaust port 10 prevent fluid from exhausting from the right-hand end of the cylinder 30, but it also prevents fluid from exhausting from the lefthand end of the cylinder 30, and the fluid is, of course, a liquid, preferably oil, and as such incompressible. Furthermore, as will be seen in Figure 2, even the entrance ports 59 and 69 are blocked. The grinding wheel, therefore, grinds the work piece at the end of the traverse stroke over a length equal to'the width of the wheel as long as the dwell continues.

Referring now to Figure 2, the valve piston 53, when the table has stopped, has just closed the port 18. The aforesaid spring action is now moving the valve member 49 to the right and fluid is forced out of the chamber 80 through a port 8| into a chamber 83 which is connected by a pipe 85 with a needle valve 81. On the other side of the valve 45 (which is symmetrical, as will be observed), a port 82 opens into a chamber 84 which is connected by a pipe 86 to a needle valve 88. The needle valves 81 and 88, respectively, are connected by pipes 89 and 99, respectively, with reservoirs 9| and 92, respectively, formed in the upper side of the casing of the valve 45. These reservoirs 9| and 92 have ports 93 and 94 connected to the chambers 83 and 84, respectively. The ports 93 and 94 are closed by ball check valves 95 and 96, but open automatically when the pressure is released to allow the oil to flow downwardly.

So far as certain features of the invention are concerned, the dwell control might be embodied in a separate or self-contained unit. But whenever the valve member 49 moves to the right beyond the position shown in Figure 2 or to the left beyond the position shown in Figure '1, oil is forced through the needle valve 81 or 88, respectively, because the valve piston 53 is greater in area than the valve piston 54 and the valve piston is greater in area than the valve piston 50. This forces the valve member 49 to move slowly under the aforesaid spring pressure, and in fact by careful adjustment of the needle valves 81 and 88 a dwell of any length within wide limits can be provided at either end of the stroke. Finally, however, when the valve member 49 has reached the position shown in Figure 3, the piston portion 54 has uncovered a large port 91 which, as shown in Figure 5, is connected by an annular chamber 99 in the valve casing 45 with a vertical passage IOI in the valve casing of the valve 45 which leads to the bottom of the reservoir 9!. On the other side of the valve 45 there is a port 98 similar to the port 91 which is similarly connected to the reservoir 92, this being represented diagrammatically in Figure 1 by pipes IOI and I02 connecting the ports 91 and 98 with the reservoirs 9| oil.

Coincidentally with the uncovering of the large port 91 for free flow of oil out of the chamber 80 into the reservoir 9 I, the port 11 is uncovered and thus oil is admitted to the chamber 19 which causes pressure fluid movement of the valve member 49, no longer under the control of the needle valve 81, and the valve member 49 is accordingly rapidly moved to a full open position exactly opposite to. that shown in Figure 1. Consequently the table II now moves rapidly to the right and is in similar fashion reversed again at the right-hand end of its stroke, all under the control of the needle valve 88.

Referring to Figures 1, 4 and 7, a speed control or throttle valve casing I05 is connected to the casing of the valve 45. In the casing I05 is a valve member I06 having piston portions I01 and I08. The casing I05 is provided with a V- shaped port I09 which is located at one end of a passage I I 0 (shown in part as a pipe I Illa, in Figure 1) leading from the exhaust port 10. A passage or outlet pipe III serves to exhaust fluid from a throttle valve chamber I I2 into the reservoir within the base of the machine. The throttle valve is thus located in the exhaust side of the system so as to maintain pressure in the cylinder 30.

The throttle valve member I06 is arranged so that it may be rotated and also moved axially. In the preferred construction, the end of the valve piston I08 is a plane surface which, instead of being at right angles to the axis of the valve member I06, is arranged at an angle thereto. By rotating the member I06, a fine adjustment of the throttling action may be obtained, more or less of the V-port I09 being out 01f. Referring to Figure 7, a gear II3 with V shaped teeth is formed on the member I06 and a spring-pressed pawl II 4 is carried by the valve casing, thus resiliently holding the valve member I06 in adjusted position. At the same time this allows the valve I06 to be moved (in a manner more fully disclosed in the aforesaid patent to Wood) and 92 for free flow of flanged collars I 58.

to bring a valve chamber I I5 into position to connect chambers 66 and 61 (extended on Figure 1 by pipes 66a and 61a) to by-pass the fluid between the ends of the cylinder 30, thereby stopping the table in any desired position.

Referring now to Figures 4, '7 and 8, the reversing lever 20 is fastened to the front end of a shaft I20 which is journalled in a casing We on the base I0. Fastened to the rear end of the shaft I20 by means of a key IZI and a nut I22 is a hub I23 of an arm I24. The arm I24 has a hole I25 therein through which passes a pin I26 projecting forwardly from an arm I21 that is journalled on the hub I23. The pin I26 fits loosely in thehole I25, thus providing a lost motion connection between the arms I24 and I21. A spring I28 fits partly in a casing I29 and partly in a similar casing I30, respectively formed in the arms I24 and I21, and thereby urges them into angular alignment while permitting a few degrees of angular displacement between them. Projecting rearwardly from the arm I21 is an actuating pin I3I which fits in a groove I32 in the valve member 49. Thus, as before stated, the valve member 49 and the reversing lever 20 are connected by a lost motion connection and a spring which provides the spring actuation of the valve member 49 previously referred to.

The needle valves may be of any desired type but, as shown in Figure 1, may comprise valve casings I50 having chambers I5I and I52 separated by webs I53 in which are openings just fitting needles I54 on the end of spindles I55 which have screw threaded portions I56 engaging internally screw threaded portions in cap members I51 the tops of which are closed by The spindles I55 may be turned by wheels I60. This construction permits accurate adjustment of the dwell and the needle valves can be closed so tightly that the machine will stop altogether with the table in the dwell position and can be opened so wide that reversal is fairly rapid and may be adjusted to any intermediate position.

In the operation of the machine the table II supports in any suitable way a work piece or a grinding wheel to move one in relation to the other. The traversing and reversing mechanism herein described reciprocates the table II, causing it to stop at each end of the stroke for a length of time determined by the adjustment of the respective needle valves 81 and 88. For example, when the table is moving to the left, the valve 49 is in the position shown in Figure 1. When the dog I3 strikes the projection I9 of the reversing lever 20, the spring I28 is compressed because there is pressure in the chamber resisting movement of the valve member 49. When, however, the side of the hole I25 reaches the pin I26, the valve member 49 is moved to the position shown in Figure 2, thus stopping the table and holding it rigidly in position. The valve member 49 now moves from the position shown in Figure 2 to the position shown in Figure 3 solely by the action of the spring I28 resisted by the needle valve 81 which, of course, may be adjusted to any position desired by the handle I60. As well shown in Figures 2, 3 and '7, the balls and 96 nearly fill the chambers 83 and 84 and thus they quickly check the flow of oil through the ports 93 and 94 and the needle valves 81 and 88 govern the dwell.

The dwell is ended when the valve member 49 reaches the position shown in Figure 3 for at that time the port 91 is opened and the fluid fiows freely outwardly from the chamber 80. At the same time, fluid enters the chamber I9 and the valve member 49 moves by pilot actuation until the right-hand side of the valve member 53 contacts a shoulder I65 in the chamber 80. By that time the table I l is rapidly moving to the right. The actuation of the valve 59 is, therefore, mechanical from the position shown in Figure 1 to the position shown in Figure 2, by spring pressure from the position shown in Figure 2 to the position shown in Figure 3, and by fluid pressure. pilot actuation from the position shown in Figure 3 onward to a position exactly opposite to that shown in Figure 1. Since the valve is symmetrical and all chambers, ports and pipes are duplicated at each side of the machine, reversal at one end of the stroke takes place in the same manner as reversal at the other end of the stroke, the valve member 49 being held at the left-hand end of the stroke by a shoulder ,l 66. However, the time period of the dwell can be varied within wide limits by adjusting the needle valves 8'! and 88.

In accordance with the cross feed mechanism fully described in the patent to Wood referred to, the grinding wheel is fed into the work piece at the commencement of the dwell. The parts and connections causing this infeed are not herein shown since they may be identical with those shown in the patent to Wood referred to, and they fit into the parts and the fluid pressure system herein shown without any interference whatsoever, as will readily be seen bycomparing this application with the patent to Wood referred to. This is an advantage because the end portions of the locus of the work piece which is being ground can b ground right down to the smallest diameter during the dwells and then during the traverse of the table the center portion of the work piece can be level to these end portions, resulting in a work piece of uniform diameter.

The reason why I provide reservoirs 9| and 92 above the valve member 49 is so that when either the chamber 19 or is enlarging, oil will be provided to fill it either through passage 91 or 98 at the start or through passage 8| or 82 later on. Thus air is kept out of the system. If air is allowed to enter the fluid pressure system, irregular movements of the valves and table result.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

A reversing valve mechanism comprising a valve casing, a movable valve member in said casing, a reversing lever, a lost motion connection between said valve member and said reversing lever, a spring also connecting said valve member to said lever, piston and cylinder means mechanically connected to said valve member, a restricted orifice connected to said cylinder, a pilot actuating device mechanically connected to said valve member, and a large orifice also connected to said cylinder, the parts being so arranged that when the reversing lever is moved the spring is loaded and the valve member moves at a rate determined by the size of the restricted orifice until the large orifice is uncovered, at which time the pilot actuated device shifts the movable valve member the remaining distance to cause reversal of an operating part.

CARL G. FLYGARE. 

